Decelerometer



Feb. 22, 1938. 1 ALDEN 2,108,791

DECELEROMETER Filed March 1, 1955 2 Sheets-Sheet 2 I [I'll III/11.1111

INVENTOR Rio/1mm J1]; om

.LQW/

ATTORNEYS Patented Feb. 22, 1938 DECELEROMETER Reginald J. Alden, New York, N. Y., assignor to Chapin & Neal, Springfield, Mass, a iirm Application March 1, 1935, Serial No. 8,921

Claims.

This invention relates to decelerometers for use in testing the operation of the braking system 01' motor cars and the like. -More particularly it relates to a decelerometer of the type 5 in which a body, moving under the influence of the momentum imparted'by the original motion of the car, gives successive indication as the car-is abruptly slowed down by the application of thebrakes.

One object of the invention is to provide a simple and inexpensive but reliable device for the above purpose suitable for use as a permanent or semi-permanent car instrument, or as an auxiliary instrument to be temporarily placed in the car for the period of the test.

Another object of the invention is the provision of an instrument of this class, in which the indications given as the inertia actuated body moves to its final indicating position are not repeated in reverse direction as the body returns to rest position.

A further object is to provide an instrument of this class in which the indicator of the instrument persists until released or at least for a period suflicient to afford ample time for a deliberate inspection of the reading.

Other and further objects residing in the construction and arrangement of the parts will be obvious from the following specification and claims. I

In the accompanying drawings:

Fig. 1 is a front view of an instrument according to the present invention;

Fig. 2 is a sectional view substantially on line 2-2 of F18. 1;

Fig. 3 is a sectional view substantially on line 33 of Fig. 2;

Fig. 4 is a fragmentary sectional view substantially on line H of Fig. 2;

Fig. 5 is a detail view of the mercury containing member with the cover plate removed;

, Fig. 6 is a fragmentary sectional view substantially on line 6-6 of Fig. 1;

Fig. '1 is a diagrammatic view of the electrical 45 circuit of the device;

Fig. 8 is a front view of an alternative form of the invention;

Fig. 9 is a sectional view substantially on line 9-9 of mg. 8; I

Fig. 10 is a sectional view substantially on line ll-ll of Fig. 9;

Fig. 11 is a sectional view substantially on line ll|l of Fig. 10;

Fig. 12 is a fragmentary sectional view substantially on line I2-l2 of Fig. 10, the lamp bulb being removed; and

Fig. 13 is a detail view partly in section showing a modified form of lamp mounting.

Referring to Figs. 1 to '7 of the drawings, l indicates a cup-like casing, formed of bakelite or other suitable material provided with a closure 2 which forms the front face of the instrument. The closure member is provided with spaced window openings 3 and 4 respectively provided with panes 5 and 6 of transparent material, such as glass or celluloid colored red and green respectively. The cover may be provided adjacent the openings with descriptive indicia as indicated at 8, if desired.

A flat, generally rectangular member ill which carries the operating parts of the device is positioned vertically within the casing i intermediate the windows and is held in place by the tightness of its fit or in any other suitable manner.

The member l0 comprises a body plate I I, provided with an endless groove l2, and a cover plate I3 which is tightly secured to the body plate by screws l4, forming groove I2 into a closed channel. Plates II and [3 are formed of bakelite or other suitable non-conducting material. The groove or channel [2, best shown in Fig. 7, has a vertical portion 15, a lower horizontal portion IS, a forwardly inclined portion l1 and an upper horizontal portion l8. An electrical contact I9 passes through the member l0 into portion I5 of the channel and two similar contacts 29 and 2| are positioned in spaced relation in the inclined portion of the channel. A quantity of mercury indicated at 22 in Figs.

5 and '7 is enclosed in channel l2.

Member III is formed with a generally rectangular opening 25, having a vertical slot 26 extending downwardly therefrom. A metal bar 21 is provided at its ends with electric light sockets 29 and 29. Opening 25 is of a size to permit one end of the bar 21 and the socket carried thereby to be passed through after which the bar is moved downwardly to wedge the bar tightly in slot 26 and position the sockets 28 and 29 respectively opposite the window openings 3 and 4 so that when electric bulbs 30 and 3| are positioned in the sockets and lighted the colored panes in the window openings are illuminated.

A conductor 33 connects contact I!) with the central terminal of socket 28, the other terminal of said socket being connected through bar 21 and conductor 34 to the ground of the electrical system. Contact 2| is connected by conductor 36 to the central terminal of socket 29, the other terminal of which is grounded through bar' 31 and conductor 34.

Contact 20 is provided outwardly of the member III with a freely swinging pendulum switch member 31', the lower end 33 of which-is adapted to swing into abutting engagement with cooperatin'g switch member 33 as later more fully described. Member 31 is preferably counterbalanced above the pivot 20 as indicated at 40.

Member 35 is connected by a conductor ll to a .source of electric current such as battery 42 which may be the battery of the motor car where the instrument is permanently or semi-permanently installed in the car. .The other terminal of the battery is grounded as indicated at 43. Having reference to Fig. 7 the operation of the structure so fardescribed may be briefly sum-\ marized as follows. With the car travelling at a uniform speed the parts are in the position shown in Fig. '7 and it will be evident that the circuits through both lamps are open. If new the brakes are applied to bring the car to rest the inertia of the mercury in portions l8 and ll of .the tube causes the mercury to advance in'the tube to bring the mercury into engagement with contact 20, and at the same time pendulum switch member is thrown forward by its own inertia into abutting contact with member 39 to close the circuit between contact 20 and the battery 42. The quantity of mercury is such and the contacts I9, 20 and II so spaced that the forward movement of the mercury first connects the contacts I! and 20 closing the circuit through the red lamp 30 and; if the deceleration of the car is sufficiently abrupt the resulting continued movement of the mercury causes it to leave contact i9 and continue up the inclined portion of the tube, thus opening the circuit through iamp 30, and connecting contacts 20 and 2i to close the circuit through the green lamp 3i. Upon substantial completion of the deceleration of the car, that is when the car iseither brought quickly to substantially a state of rest, or its rate of deceleration is decreased to a degree where the movement of the car so nearly approximates uniform motion that the mercury starts tofall back in the tube under the action of gravity. the switch member 31 also under the action of gravity, falls away from contact 39. Suchmovement of member 31 instantly opens the circuit between contact 20 and the battery, with the result that the green light is extinguished and the red lamp is not lightedwhen the mercury, in its return movement again connects members l9 and 2B. The rearward swing of the pendulum member 39 is halted by a rod 44 which brings member 39 to rest in normal positlon. M

It is sometimes desirable to hold the mercury so in its forward position a suiiicient length of time to permit inspection and reading of the instrument after the car has been brought to rest and for this purpose the channel [2 is provided with an enlarged cylindrical portion 45 in the verti- 05 cal arm l5 of the channel just below contact IS.

A steel balN5 positioned in the cylindrical portion .5 acts as a check valve to prevent the immediate return of the mercury into normal position in the channel', thus maintaining the mercury in whatever circuit closing position it has assumed in response to the rate of deceleration of the car. This preservation of the reading of the instrument is made dependent on the will of the operator by controlling pendulum switch 31 which normally would open the battery circuit glass, celluloid or the like.

' the reading observed the circuit may be broken by as soon as or shortly before the carcomes to rest. This control is accomplished by means of an eccentric cam' secured to rod ll. Rod 44 extends through casing I and as best shown in Fig; 4 is provided with a handle 4! by which the operator may rotate rod 54 and cam 45 to move pendulum member 31 into contact with member 35 as shown in dotted line in Fig. 7 and hold it there...

After the car has been broughtto a stop and 10 turning handle I! to return cam II to' the full line position of Fig. 7, thus releasing pendulum member 31. Vibration of the car during a short period of subsequent operation causes sumcient vibration or ball "to permit the mercury to slowly assume its normal position.

In Figs. 8 to 13 is shown an alternate arrangement in, which an eccentrically weighted cylinder'acting like a pendulum-is employed as the inertia actuated member. As shown in said figures this alternative form comprises a box-like casing 50 formed of bakelite or other suitable material. The open side of the casing is provided with a closure plate ll, of similar material, removably. secured to the casing by screws 52. One face of the casing is formed with a window opening 53 provided with a clear pane 54 of A cup-like cylindrical member 55 secured to a metal shaft 55 is rotatably mounted in the casing by means of trunnions 51 and 58 formed on the ends of shaft 56 and engaging in bearing recesses 55 and ill respectively formed in a metal strip I5 set in cover plate 5| and the opposite wall 5| of the easing. The open end of the cylinder 55 is positioned adjacent the cover plate 5! and the latter plate is provided with an electric light socket 52 adapted to receive a lamp bulb 63 which projects into the cylinder 55 opposite window 53. Cylinder 55, as best shown in Fig. 9, is provided with spaced window openings 55 and respectively p vided with red and green panes 61 and 58, f0 ed of glass, celluloid or the like, which panes re arranged to be brought successively into registration with the window opening 53 and bulb 53 upon rotation of the cylinder in the direction of the arrow in Fig. 9. The cylinder 55 is provided with a weight III which as shown is provided with a threaded stud II engaging in a suitably threaded opening in the cylinder. As shown in Fig. 9 the parts are so arranged that in normal position, as when the car by which the instrument is carried, is in uniform motion, an unbroken portion of the cylinder is interposed between lamp 53 and window 54. As the car decelerates under the application of its brakes the inertia of the weight 10 causes cylinder 55 to rotate about its 1 red window between opening 53 and the lamp and axis in the direction of the arrow to bring the 60 if the rate of deceleration is suflicient the further movement of the weight advances the cylinder to move the green window into position between opening 53 and the lamp.

Lamp 53 is provided with current from the car's battery or other suitable source, the circuit arrangement being best indicated in Fig. 10. The central terminalof socket 52 is grounded by a conductor I5, the other socket terminal being connected by metal strip I5, to the metal shaft 56. A freely swinging pendulum switch member ll similar to member 31 previously described is rotatably mounted on shaft 55 between strip 15 and a collar I8 formed on the shaft. The

lower end of member 11 is adapted to be swung 7s into contact with a contact pin 19 secured in cover plate 5| and connected by a conductor 80 to the car battery, diagrammatically indicated at II, the other terminal of the battery being grounded as indicated at 82. As in the previously described structure a rod 63, see Figs. 11 and 12, serves to arrest the return swing of member 11. Rod 83, which extends outside of the casing is provided with a handle 84, and carries a cam 85 adapted to releasably hold the switch members 11-19 closed when the reading of the instrument is temporarily preserved by restraining the return of the drum to normal position. Such restraint of the drum may be accomplished by means of a flexible reed 06 secured to rod 83, and normally positioned as shown in full lines in Fig. 12. When the instrument reading is to be preserved rotation of handle 84 moves cam 85 into switch closing position and simultaneously swings reed 86 into the path of lugs 81 formed on the inside of drum 55. The reed 86 is sufllciently flexible so that the lugs l1 brush by it as the drum is rotated by the inertia of weight 10 but when the limit of rotation is reached the resistance of the reed is suflicient to sustain the dead on balance weight of member 10 and the reading is preserved until the subsequent vibration of the car in operation jars the drum back to normal position.

It will be evident that in ordinary operation deceleration of the car causes switch member 11 to move into contact with member 19 closing the circuit and lighting lamp 63, and that simultaneously drum 55 is rotated by the inertia of weight 10 to bring window 61, or windows 61 and 68 in succession between opening 54 and the lighted lamp, the extent of movement of the drum depending on the rate of deceleration. When the reading of the instrument is to be temporarily "preserved handle 8| is operated to manually close switch 11-19, thus lighting the lamp and maintaining it lighted, while at the same time retaining reed 86 is moved into operative position.

Excessive over-travel oi! the drum in the reverse direction is prevented by a stop 90 secured to the bottom of the casing and positioned to be engaged by the projecting stud ll of the weight.

If desired the conventional socket 62 may be omitted and the lamp bulb directly threaded into strip 15 and the cover plate 5| as indicated at ill and the central bulb termination is connected to conductor 15 by a spring contact 92 secured -of movement of the mercury, the spaces between the contacts forming gaps in said electrical circuits, said gaps being successively closed by the movement of the mercury along the channel to successively actuate said signal means in a predetermined sequence and inertia operated switch means controlling said circuits independently of the movement of the body of mercury and operative upon the substantial completion of the deceleration of the car to open said circuits.

2. A deceleromotor for use in motor cars which comprises a plurality of electrically operated signal means indicative of predetermined rates of deceleration, parallel electric circuits respectively controlling said signal means, a member having a closed channel formed therein, a body of mercury enclosed in the channel, said body of mercury being movable within the channel in response to the deceleration of the car, a plurality of spaced electrical contacts positioned in the channel in the path of movement of the mercury, the spaces between the contacts each forming a gap in one of said parallel circuits, said gaps being successively closed by the movement of the mercury along the channel to successively actuate said signal means in a predetermined sequence and an inertia operated switch positioned in series with each of said gaps in said parallel circuits and operative upon the substantial completion of the deceleration of the car to open said circuits. 7

3. A deceleromotor for use in motor cars which comprises a plurality of electrically operated signal means indicative of predetermined rates of deceleration, electric circuits controlling said signal means, a member having a closed channel formed therein, a body of mercury enclosed in the channel, said body of mercury being movable within the channel in response to the deceleration of the car, a plurality of spaced electrical contacts positioned in the channel in the path of movement of the mercury, the spaces between the contacts forming gaps in said electrical circuits, said gaps being successively closed by the movement of the mercury along the channel to successively actuate said signal means in a predetermined sequence, an inertia operated switch member normally controlling said circuits independently of the movement of the body of mercury-and operative upon the substantial completion of the deceleration of the car to open said circuits, manually operated means for controlling said switch member and a check valve in said channel to releasably restrain return of the mercury along the channel.

4. A deceleromotor for use in motor cars which comprises, signal means to indicate an unsafe rate of deceleration, and signal means to indicate a safe rate of deceleration, an oscillatory signal actuating member normally held in inoperative position by gravity and movable by its inertia to successively actuate and deactuate said unsafe signal means and actuate said safe signal means, in response to predetermined rates of deceleration, and returnable toqits inoperative position by gravity upon substantial completion of the deceleration of the car, and means automatically operative in response to the substantial completion of the deceleration of the car to prevent reactuation of the unsafe signal means during the return movement of said signal actuating member after actuation of the safe signal means.

5. A deceleromotor for use in motor cars which comprises, signal means to indicate an unsafe rate of deceleration, and signal means to indicate a safe rate of deceleration, an oscillatory signal actuating member normally held in inomrative position by gravity and movable by its inertia to successively actuate and deactuate said unsafe signal means and actuate said safe signal means, in response to predetermined rates of deceleration, and returnable to its inoperative position by gravity upon substantial completion of the deceleration of the car, means inoperative position, and means manually operable by the operator to inhibit operation of the said reactuation preventing meanato thereby render said restraining means elective to preserve the final indication of the signal means.

REGINALD J. ALDEN. 

